Close-coupled catalytic converter

ABSTRACT

A close-coupled catalytic converter according to an exemplary embodiment of the present invention includes: a front catalyst and a rear catalyst that are cylindrically shaped, coated with a metal catalyst, and disposed separately from each other; and a catalyst cover including an upper shell and a lower shell, and the upper and lower shells are semi-cylindrically shaped, wherein an end of the catalyst cover is connected with a front muffler pipe that is connected with an exhaust manifold and the other end of the catalyst cover is connected with a rear muffler pipe that emits an exhaust gas. The structures of a shell for a catalyst and for configuration of an oxygen sensor are simplified so that manufacturing process and cost are reduced and purifying performance is enhanced. Since back pressure is reduced, engine performance is enhanced.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2006-0097328 filed in the Korean IntellectualProperty Office on Oct. 02, 2006, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a close-coupled catalytic converter.More particularly, the present invention relates to a close-coupledcatalytic converter in which a structure of a shell for a catalyst and astructure for configuration of an oxygen sensor are simplified so thatconfiguration performance is enhanced, and a rate of coating of a frontcatalyst is optimized so that efficiency of the catalytic converter isenhanced and manufacturing cost is reduced.

(b) Description of the Related Art

A catalytic converter (or a catalyst converter) is a device thatconverts carbon monoxide, hydrocarbon, nitrous oxide, and so on,contained in an exhaust gas into a harmless material like water, carbondioxide, and so on.

Conventional catalytic converters have a substrate coated with a metalfor a catalyst, and the substrate is supported by a mat and disposed ina metal shell. Platinum (Pt), rhodium (Rh), or palladium (Pd) is usedfor coating the substrate.

The conventional catalytic converter can be classified according toposition as a manifold catalytic converter (or a warm-up catalyticconverter) that is directly connected with an exhaust manifold, anunder-floor catalytic converter (UCC) that is separated from an exhaustmanifold and configured on a vehicle floor in the middle of a mufflerpipe, and a close-coupled catalytic converter (CCC converter) that isseparated from an exhaust manifold but is closer than the under-floorcatalytic converter. A catalytic converter configures one or twocatalysts according to requirement.

FIG. 1 a and FIG. 1 b are a schematic diagram and a perspective view ofa conventional CCC catalytic converter, respectively, and FIG. 2 is aschematic diagram of another conventional CCC catalytic converter.

As shown in FIG. 1 a and FIG. 1 b, a conventional CCC catalyticconverter 1 configures two different catalysts 5 that are almostcontacted with each other and inserted into one shell 3, and theconventional CCC catalytic converter 1 is disposed away from an exhaustmanifold 7 and emits an exhaust gas. Oxygen sensors 9 are disposed at aforwards part and a rearwards part of the conventional CCC catalyticconverter 1, and the conventional CCC catalytic converter 1 iscontrolled by a theoretical air/fuel ratio.

However, the two catalysts 5 in the conventional CCC catalytic converter1 are almost contacted with each, other so that efficiency of across-section of a rear catalyst is reduced.

As shown in FIG. 2, a front catalyst 11 and a rear catalyst 13 ofanother conventional CCC catalytic converter 10 are disposed in a frontshell 15 and a rear shell 17 respectively, and connected by a centercone 14. The front catalyst 11 is connected to an exhaust manifold by afront cone 12 that is disposed forward of the front catalyst 11, and therear catalyst 13 is connected to a muffler pipe by a rear cone 16 thatis disposed rearward of the rear catalyst 13. In this case, an oxygencatalyst is configured in the front cone 12 and the center cone 14respectively.

However, this conventional catalytic converter requires a plurality ofcones and shells so that a manufacturing cost of canning is high, andalso requires a plurality of welding processes so that the manufacturingprocess is increased.

When an oxygen sensor is configured to the conventional CCC catalyticconverter, a cylindrical boss is fixed to a shell by welding so that aconfiguration angle of the oxygen sensor is limited by a shape of theshell. Therefore, when the configuration angle of the oxygen sensor ischanged, a shape of the shell must be changed.

Because of a size of a diameter of a front shell, an assembly tool mayoften interfere with the shell during assembly of the shell to anexhaust manifold, a pipe, and so on. A front catalyst must be disposedas close as possible near an engine in order that a catalytic converterreaches a light-off temperature (a temperature of activating thecatalyst) quickly. However, it is difficult to dispose the frontcatalyst near an engine because of the above-mentioned interference.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide aclose-coupled catalytic converter having the advantages that a structureof a shell for a catalyst and a structure for configuration of an oxygensensor are simplified so that configuration performance is enhanced, anda rate of coating of a front catalyst is optimized so that efficiency ofthe catalytic converter is enhanced and manufacturing cost is reduced.

Also the present invention has been made in an effort to provide aclose-coupled catalytic converter having the advantages that a frontcatalyst is closely disposed near an engine so that the light-offcharacteristic is improved, a coating ratio of a front catalyst isoptimized, and efficiency of a cross-section of a rear catalyst isimproved so that efficiency of a CCC catalytic converter is improved.

A CCC catalytic converter according to an exemplary embodiment of thepresent invention includes: a front catalyst and a rear catalyst thatare cylindrically shaped, coated with a metal catalyst, and disposedseparately from each other; and a catalyst cover including an uppershell that covens upper parts of the front catalyst and the rearcatalyst and a lower shell that covers lower parts of the front catalystand the rear catalyst, and the upper and lower shells aresemi-cylindrically shaped, wherein an end of the catalyst cover isconnected with a front muffler pipe that is connected with an exhaustmanifold and the other end of the catalyst cover is connected with arear muffler pipe that emits an exhaust gas.

An oxygen sensor may be disposed between the front catalyst and the rearcatalyst.

The oxygen sensor may be inserted into an oxygen sensor boss that isformed along a circumference shape of the upper shell and the lowershell so that one edge of the oxygen sensor boss is longer than theother edge.

The oxygen sensor boss may have an internal surface that is manufacturedaccording to a configuration angle of the oxygen sensor.

A diameter of the front catalyst may be a first predetermined length inorder not to interfere with an assembly tool for assembling the lowershell and the front muffler pipe.

The front catalyst may be disposed near to the front muffler pipe at asecond predetermined length in order to reduce a time to reach atemperature of activating the catalyst.

A length of the front catalyst may be shorter than that of the rearcatalyst.

The front catalyst may include a first coating portion and a secondcoating portion that are coated with a different amount and a differentkind of a metal catalyst respectively.

The catalyst cover may be protrusive at the front catalyst and the rearcatalyst, and the catalyst cover may be concaved at a front part of thefront catalyst, at a rear part of the rear catalyst, and at a partbetween the front catalyst and the rear catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will now bedescribed in detail with reference to certain exemplary embodimentsthereof illustrated the accompanying drawings which are givenhereinbelow by way of illustration only, and thus are not limitative ofthe present invention, and wherein:

FIG. 1 a and FIG. 1 b are a schematic diagram and a perspective view ofa conventional CCC catalytic converter respectively;

FIG. 2 is a schematic diagram of another conventional CCC catalyticconverter;

FIG. 3 is schematic diagram of a CCC catalytic converter according to anexemplary embodiment of the present invention;

FIG. 4 is a perspective view of the CCC catalytic converter according toan exemplary embodiment of the present invention;

FIG. 5 is an internal perspective view of the CCC catalytic converteraccording to an exemplary embodiment of the present invention;

FIG. 6 is a bottom side perspective view of the CCC catalytic converteraccording to an exemplary embodiment of the present invention;

FIG. 7 a and 7 b are a partial cross-sectional view and a perspectiveview of the CCC catalytic converter respectively showing a configurationof an oxygen sensor boss according to an exemplary embodiment of thepresent invention;

FIG. 8 is a schematic diagram of the CCC catalytic converter accordingto an exemplary embodiment of the present invention showing assembly ofa coating state;

FIG. 9 is a perspective view of the CCC catalytic converter according toan exemplary embodiment of the present invention showing assembly of acatalyst cover and a front muffler pipe, with an assembly tool; and

FIG. 10 is an analysis diagram showing flow improvement by comparing theuniform distribution rate of fluid velocity at a cross-section of asubstrate of the CCC catalytic converter according to an exemplaryembodiment of the present invention with the uniform distribution rateof fluid velocity at a cross-section of a substrate of a conventionalCCC catalytic converter.

DESCRIPTION OF REFERENCE NUMERALS INDICATING PRIMARY ELEMENTS IN THEDRAWINGS

100: CCC catalytic converter 110: catalyst cover 112: lower shell 114:upper shell 120: oxygen sensor boss 122: oxygen sensor 130: frontcatalyst 132: first coating portion 134: second coating portion 140:rear catalyst 200: exhaust manifold 300: front muffler pipe 400: rearmuffler pipe 500: assembly tool

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variouspreferred features illustrative of the basic principles of theinvention. The specific design features of the present invention asdisclosed herein, including, for example, specific dimensions,orientations, locations, and shapes will be determined in part by theparticular intended application and use environment. Certain features ofthe illustrated embodiments have been enlarged or distorted relative toothers to facilitate visualization and clear understanding.

In the figures, reference numbers refer to the same or equivalent partsof the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter reference will now be made in detail to various embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings and described below. While the invention will bedescribed in conjunction with exemplary embodiments, it will beunderstood that present description is not intended to limit theinvention to those exemplary embodiments. On the contrary, the inventionis intended to cover not only the exemplary embodiments, but alsovarious alternatives, modifications, equivalents and other embodiments,which may be included within the spirit and scope of the invention asdefined by the appended claims.

FIG. 3 is schematic diagram of a CCC catalytic converter according to anexemplary embodiment of the present invention. FIG. 4 is a perspectiveview of the CCC catalytic converter according to an exemplary embodimentof the present invention, and FIG. 5 is an internal perspective view ofthe CCC catalytic converter according to an exemplary embodiment of thepresent invention. FIG. 6 is a bottom side perspective view of the CCCcatalytic converter according to an exemplary embodiment of the presentinvention, FIG. 7 a and 7 b are respectively a partial cross-sectionalview and a perspective view of the CCC catalytic converter showingconfiguration of an oxygen sensor boss according to an exemplaryembodiment of the present invention, and FIG. 8 is a schematic diagramof the CCC catalytic converter according to an exemplary embodiment ofthe present invention showing assembly of a coating state. FIG. 9 is aperspective view of the CCC catalytic converter according to anexemplary embodiment of the present invention showing assembly of acatalyst cover and a front muffler pipe, and FIG. 10 is an analysisdiagram showing flow improvement by comparing the uniform distributionrate of fluid velocity at a cross-section of a substrate of the CCCcatalytic converter according to an exemplary embodiment of the presentinvention with the uniform distribution rate of fluid velocity at across-section, of a substrate of a conventional CCC catalytic converter.

As shown in FIG. 3 to FIG. 8, a close-coupled catalytic converter (CCCconverter) according to an exemplary embodiment of the present inventionincludes a catalyst cover 110 including a lower shell 112 and an uppershell 114, a oxygen sensor 122 disposed on the lower shell 112, and afront catalyst 130 and a rear catalyst 140 that are coated with a metalcatalyst for purifying an exhaust gas and are disposed in the lowershell 112 and the upper shell 114.

A front connecting flange 112 a is formed at an end of the CCC catalyticconverter 100 and the front connecting, flange 112 a connects the CCCcatalytic converter 100 with a front muffler pipe 300 that is connectedto an exhaust manifold 200. A rear connecting flange 112 b is formed atthe other end of the CCC catalytic converter 100 and the rear connectingflange 112 b connects the CCC catalytic converter 100 with a rearmuffler pipe 400 that emits an exhaust gas passing through the CCCcatalytic converter 100.

The CCC catalytic converter 100 includes the upper shell 114, whichcovers an upper part of the front catalyst 130 and the rear catalyst140, and the lower shell 112, which covers a lower part of the frontcatalyst 130 and the rear catalyst 140, wherein the upper shell 114 andthe lower shell 112 are semi-cylindrically shaped.

The catalyst cover 110 is protrusive at the front catalyst 130 and therear catalyst 140, and the catalyst cover 110 is concaved at a frontpart of the front catalyst 130, at a rear part of the rear catalyst 140,and at a part between the front catalyst 130 and the rear catalyst 140.

The lower shell 112 and the upper shell 114 may be connected by aprotrusion, a hook, inserting, or welding. However, the CCC catalyticconverter 100 according to an exemplary embodiment of the presentinvention is integrally formed by canning without a connecting cone orredundant welding. Therefore, a manufacturing cost of the CCC catalyticconverter 100 may be reduced and a welding process may be minimized.

As shown in FIG. 6, an oxygen sensor boss 120 is formed on the lowershell 112 for configuring an oxygen sensor 122.

As shown in FIG. 7, an oxygen sensor boss 120 is fixed to the lowershell 112 that is rounded so that the oxygen sensor boss 120 is formedalong a circumference shape of the lower shell 112 and one edge of theoxygen sensor boss 120 is longer than the other edge. That is, the shapeof the oxygen sensor boss 120 is a dissymmetrical cylinder.

Thus, it is inclined gradually from an upper part of the lower shell 112to a lower part of the lower shell 112 so that a length of an upper halfof the cylinder is shorter than that of a lower half of the cylinder.

An internal surface of the oxygen sensor boss is manufactured in astraight line or a curved line according to a configuration angle of theoxygen sensor 122. So, when the configuration angle of the oxygen sensor122 is changed, a shape of the shell 112 is not required to be changed.Thus, just changing the internal surface of the oxygen sensor boss 120can correspond to changing the configuration angle of the oxygen sensor122.

As shown in FIG. 8, the front catalyst 130 includes a first coatingportion 132 and a second coating portion 134 that are coated with adifferent amount and a different kind of a metal catalyst respectively.

The first coating portion 132 may be coated with palladium (Pd) and thesecond coating portion 134 may be coated with a mixture of palladium(Pd) and rhodium (Rh). The larger the coating amount of the metalcatalyst, the better the ability for purifying the exhaust gas. However,a metal catalyst is expensive and so an optimized coating ratio isrequired.

In the CCC catalytic converter 100 according to an exemplary embodimentof the present invention, when a length of the first coating portion 132is determined to be 50 mm (±10 mm), a coated volume may be about 0.350,while when a length of the first coating portion 132 is determined to be40 mm, a coated volume may be about 0.270 and when a length of the firstcoating portion 132 is determined to be 60 mm, a coated volume may beabout 0.410. Various coating ratios and kinds of metal catalyst may beused according to a vehicle and an amount of exhaust gas.

As shown in FIG. 10, the front catalyst 130 and the rear catalyst 140are disposed separately. Because the front catalyst 130 and the rearcatalyst 140 are disposed separately, a mixture area of the exhaust gasis formed so that efficiency of a cross-section of rear catalyst 140 isimproved and efficiency of the CCC catalytic converter 100 is improved.In the CCC catalytic converter 100 according to an exemplary embodimentof the present invention, a uniform distribution rate of fluid velocityis increased from 0.88 in a conventional CCC catalytic converter to 0.97in the exemplary embodiment of the present invention. Namely, the rateis increased by about 10%.

As shown in FIG. 9, a diameter L6 of the front catalyst 11 shown in FIG.4 is reduced by about 12.7 mm compared to a diameter L3 of theconventional front catalyst 11 shown in FIG. 1 b, so that a space for anassembly tool to assemble the CCC catalytic converter 100 is provided.Interference of the CCC catalytic converter 100 and the assembly tool,therefore, can be prevented so that assembly process is easilyperformed.

The diameter L6 of the front catalyst 130 is a first determined length,and the first determined length can be varied according to a vehicle oran amount of exhaust gas.

A length L5 of the front catalyst 130 shown in FIG. 4 is reduced about14.7 mm compared to a length L2 of the conventional front catalyst 11shown in FIG. 1 b. Therefore, the length of the front catalyst 130 isshorter than that of the rear catalyst 140. The length of the frontcatalyst 130 may be shortened because of the optimized ratio forcoating.

A length L4 shown in FIG. 4 is shortened by about 29 mm compared to alength L1 in FIG. 1 b.

Therefore, performance of the CCC catalytic converter 100 is improvedsince the CCC converter can achieve a light-off temperature threeseconds faster than that of a conventional CCC catalytic converter 1.

The diameter, length, and position of the front catalyst 130 can bevaried according to a vehicle or an amount of the exhaust gas.

The CCC catalytic converter according to an exemplary embodiment of thepresent invention can omit a welding process compared to theconventional CCC catalytic converter 10 and does not require componentslike shells 15 and 17, cones 12, 14, and 16, or so on, so that thenumber of components can be reduced. Because a number of components canbe reduced, weight of an exhaust system can be reduced and manufacturingcost can be lowered.

According to an exemplary embodiment of the present invention, astructure of a shell for a catalyst and a structure for configuration ofan oxygen sensor are simplified so that configuration performance isenhanced, and the manufacturing process is reduced so that cost isreduced.

The performance of the CCC catalytic converter is enhanced because thecoating ratio of the front catalyst is optimized and the position of theCCC catalytic converter is close to an engine.

As described above, manufacturing cost may be reduced, weight of the CCCcatalytic converter may be lowered, back pressure may be reduced, andengine performance may be enhanced.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A close-coupled catalytic converter comprising: a front catalyst anda rear catalyst that are cylindrically shaped, coated with a metalcatalyst, and disposed separately from each other; and a catalyst covercomprising an upper shell that covers an upper part of the frontcatalyst and the rear catalyst, and a lower shell that covers a lowerpart of the front catalyst and the rear catalyst, and the upper andlower shells are semi-cylindrically shaped, wherein an end of thecatalyst cover is connected with a front muffler pipe that is connectedwith an exhaust manifold and the other end of the catalyst cover isconnected, with a rear muffler pipe that emits exhaust gas.
 2. Theclose-coupled catalytic converter of claim 1, wherein an oxygen sensoris disposed between the front catalyst and the rear catalyst.
 3. Theclose-coupled catalytic converter of claim 2, wherein the oxygen sensoris inserted into an oxygen sensor boss that is formed along acircumference shape of the upper shell and the lower shell so that oneedge of the oxygen sensor boss is longer than the other edge.
 4. Theclose-coupled catalytic converter of claim 3, wherein the oxygen sensorboss has an internal surface that is manufactured according to aconfiguration angle of the oxygen sensor.
 5. The close-coupled catalyticconverter of claim 1, wherein a diameter of the front catalyst is afirst predetermined length in order not to interfere with an assemblytool for assembling the lower shell and the front muffler pipe.
 6. Theclose-coupled catalytic converter of claim 5, wherein the front catalystis disposed near to the front muffler pipe at a second predeterminedlength in order to reduce a time to reach a temperature of activatingthe catalyst.
 7. The close-coupled catalytic converter of claim 1,wherein a length of the front catalyst is shorter than that of the rearcatalyst.
 8. The close-coupled catalytic converter of claim 1, whereinthe front catalyst comprises a first coating portion and a second,coating portion that are coated with a different amount and a differentkind of a metal catalyst respectively.
 9. The close-coupled catalyticconverter of claim 1, wherein the catalyst cover is protrusive at thefront catalyst and the rear catalyst, and the catalyst cover is concavedat a front part of the front catalyst, at a rear part of the rearcatalyst, and at a part between the front catalyst and the rearcatalyst.